Single Voice Coil.. will have one set of terminals (+,_)... this speaker has one coil as the name suggests, and is given a specific ohm load usually 4ohms or 8 ohms....

Dual Voice Coil.. will have two sets of terminals... each coil is usually 4ohms may differ however... the advantage of this speaker is you can wire it up to be either 8 ohms or wire down to 2 ohms which will pull more power from amp.. these speakers come in handy when doing multiple configurations